An arcuate or parabolic leaf spring is made by bending a generally straight and flat leaf-spring blank to the desired arc and then heat treating it to stiffen it in this shape. This bending is typically done in a machine having a fixed jaw and a movable jaw, typically referred to as the lower and upper jaw, respectively, although the reverse orientation is perfectly possible. Each jaw is provided with a plurality of shape-defining fingers that can be moved so their ends form the desired shape and then locked in place, typically with a cam arrangement.
The spring blank is set on the lower jaw and the upper jaw is moved down atop it to bend the blank into the desired shape. Then the bent blank is passed through a hot bath to heat-treat it. Such a procedure is described in "Blattfedern biegen und harten in automatischen Anlagen" ("Leaf-spring bending and hardening in automatic machines" by Hans Hermann Kallenberg, special publication of Vogelverlag Wurzburg, 29th year, Bander, Bleche, Rohre, Feb. 1989).
Such arrangements are useful with standard relatively flat leaf springs, but are not capable of forming highly arced springs, for instance of semicircular shape, as are now frequently called for. Such springs must be produced in successive stages in successive pieces of equipment.